As a conventional method for reducing intermodulation distortion generated in an amplifier or the like, a circuit including a distortion compensation circuit in the preceding or subsequent stage of the amplifier is considered. Such a distortion compensation circuit generates a specific intermodulation distortion having an amplitude whose power ratio to the desired wave is the same as that of the intermodulation distortion generated at the amplifier and having a relative phase shifted by 180 degrees with respect to the desired wave, thereby reducing the intermodulation distortion generated at the amplifier.
Conventionally, as an example of such a distortion compensation circuit, there is a circuit including an impedance transformation circuit disposed in at least one of the preceding stage and the subsequent stage of a distortion generating circuit. The impedance transformation circuit allows waves in a desired frequency band to pass through and varies the impedance in a frequency band corresponding to the difference in the frequencies of two desired waves (see, for example, Patent Literature 1).